One common structure currently employed in optical devices is the p-i-n (PIN) device. In a typical PIN device, an intrinsic layer is disposed between a p-type layer and a n-type layer, forming a heterostructure device. The intrinsic layer has a larger index of refraction than the p and n layers, resulting in a natural waveguide. Furthermore, the energy band discontinuities in carrier confinement within the active layer. In short, the PIN device is well suited for a variety of emitting and detecting optical device applications.
Presently, it is common for PIN devices to be formed as buried PIN structures. In such devices, a mesa strip is formed out of the traditional PIN device, and thereafter, blocking layers are positioned on the sides of the mesa strip. Often, the blocking layers comprise PNIN structures. After the blocking layers have been formed, it is common for a p-type (zinc) doped cladding layer to be formed thereover, thus forming a capped-mesa buried heterostructure (CMBH).
A problem that arises in CMBH structures stems from the iron doped blocking layers being in contact with the zinc doped cladding layer. Specifically, the zinc and iron inter-diffuse when subjected to high temperatures. This inter-diffusion tends to increase the device's current leakage and parasitic capacitance, both of which are very undesirable.
One approach the optoelectronics industry has attempted to reduce this inter-diffusion was to form an undoped setback layer between the doped cladding layer and the blocking layers. While the undoped setback layer reduced, or substantially eliminated, the aforementioned inter-diffusion, it misplaced the position of the p-n junction.
Accordingly, what is needed in the art is an optical device, and a method of manufacture therefor, that does not experience the drawbacks experienced by the devices disclosed above. cl SUMMARY OF THE INVENTION
To address the above-discussed deficiencies of the prior art, the present invention provides an optical device and a method of manufacture thereof. In one embodiment, the method of manufacturing the optical device includes isolating an end of a first layer from a cladding layer located over a mesa structure that has been formed from a substrate. The end of the first layer is isolated by encapsulating the end between second and third layers located adjacent the mesa structure.
The foregoing has outlined an embodiment of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional features of the invention will be described hereinafter that form the subject of the claims of the invention. Those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiment as a basis for designing or modifying other structures for carrying out the same purposes of the present invention. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the invention.